The country's biggest farm show called La Rural is held here each year as a showcase for the industry.

President Cristina Fernandez's government and farmers have been at odds since 2008 when wide protests against soy export taxes disrupted grain exports.

Argentina is the world's No. 3 soybean exporter and major supplier of beef.

The country's leading farming groups are threatening to extend the strike to the grains trade if their demands to stop what they call an illegal seizure are not met. The government says the expo center must be under the hands of the state because it is of "public use."